Skylights or domes are often added to buildings or other structures as a source of illumination or for aesthetic purposes. To give the structure thermal insulating properties, the skylights or domes are often constructed in two parts with a layer of dead air space between the inner and outer parts. The domes are usually constructed out of plastics such as acrylic plastics, and, more specifically, polymethyl methacrylate. Present techniques of installing skylights or domes usually involve the mounting of the skylight or dome in a frame made from aluminum or other suitable materials and thereafter applying a sealant, i.e., sealing composition. In addition, the labor intensive and time consuming job of priming the domes prior to sealing is often required to prevent loss of adhesion. Priming is the application of an initial adhesive coating to a surface to increase its receptivity to the main adhesive or coating.
The widely varying temperatures and moisture content of the atmosphere to which the skylights are normally exposed causes the primer or sealant to fail. This results in condensation within the dead air space between the two parts of the dome or skylight, causing a cloudy appearance, or even permitting water to leak into the interior of the building or structure. Known epoxy resins can pot dome structures. However, the resins tend to be too brittle without additives, such as flexibilizers, to withstand the humidity and temperature variations of outside weather conditions.
Although mixtures of epoxy resins and polysulfide resins are known, the art has not recognized either that the resultant resins have improved adhesion retention with respect to moisture resistance or resistance to thermal cycling. Further, the art does not teach the relative proportions of such compositions needed to impart such properties.